The formation of dental plaque leads to dental caries, gingival inflammation, periodontal disease, and eventually tooth loss. Dental plaque is a mixture of bacteria, epithelial cells, leukocytes, macrophages, and other oral exudate. Said bacteria produce highly branched polysaccharides which together with microorganisms from the oral cavity form an adhesive matrix for the continued proliferation of plaque.
As plaque continues to accumulate rock hard white or yellowish deposits arise. These deposits are called calcified plaque, calculus or tartar, and are formed in the saliva from plaque and minerals, such as in particular calcium.
Oral Polysaccharides
Oral polysaccharides are produced from sucrose introduced into the mouth, e.g. as a food or beverage constituent, by the action of cariogenic microorganisms, such as Streptococcus mutans or Streptococcus sanguis, growing in the oral cavity.
Said oral polysaccharides comprise water-soluble dextran, having large portions of .alpha.-1,6 glucosidic linkage, and a major component of water-insoluble extracellular polysaccharides called "mutan" comprised of a backbone with .alpha.-1,3-glycosidic linkages aid branches with .alpha.-1,6-glycosidic linkages.
Mutan bind to hydroxyapatite (constituting the hard outer porous layer of the teeth) and to acceptor proteins on the cell surface of said cariogenic bacteria adhering to the teeth surface.
Mutanase
Mutanases are .alpha.-1,3-glucanases (also known as .alpha.-1,3-glucanohydrolases) which degrade the .alpha.-1,3-glycosidic linkages in mutan. Mutanases have been described derived from Trichoderma (Hasegawa et al., (1969), Journal of Biological Chemistry 244, p. 5460-5470; Guggenheim and Haller, (1972), Journal of Dental Research 51, p. 394-402) and from a strain of Streptomyces (Takehara et al., (1981), Journal of Bacteriology 145, p. 729-735), Cladosporium resinae (Hare et al. (1978), Carbohydrate Research 66, p. 245-264), Pseudomonas sp. (U.S. Pat. No. 4,438,093), Flavobacterium sp. (JP 77038113), Bacillus circulanse (JP 63301738) and Aspergillus sp. A mutanase gene from Trichoderma harzianum has been cloned and sequenced (Japanese Patent No. 4-58889/A).
Dextranase
Dextranases are .alpha.-1,6-glucanases (also known as 1,6-.alpha.-D-glucan 6 glucanohydrolases) which degrade the .alpha.-1,6-glycosidic linkages in dextran. Several microorganisms are capable of producing dextranases, among them fungi of genera Penicillium, Paecilomyces, Aspergillus, Fusarium, Spicaria, Verticillium, Helminthosporium and Chaetomium; bacteria of the genera Lactobacillus, Streptococcus, Cellvibrio, Cytophaga, Brevibacterium, Pseudomonas, Corynebacterium, Arthrobacter and Flavobacterium and yeasts such as Lipomyces starkeyi.
Commercially available products include Dextranase 50 L from Novo Nordisk A/S produced by fermentation of strains of Penicillium lilacium. Dextranase 50 L is used in the sugar industry to break down dextran in raw sugar juice or syrup.
To be able to sufficiently guarantee the capability of chewing, e.g. foods, during a whole lifetime it is necessary to keep the teeth in a good condition and to obtain a good oral hygiene. This can be obtained by brushing the teeth frequently using toothpaste or the like. The mouth may further advantageously be rinsed with a mouth wash comprising anti-microbial agents.
To prevent the formation of dental caries, plaque, and tartar, it has been suggested to add a dextranase and/or a mutanase and/or other enzymes to oral care compositions and products.
U.S. Pat. No. 4,353,891 (Guggenheim et al.) concerns plaque removal using mutanase from Trichoderma harzianum CBS 243.71 to degrade mutan synthesized by cultivating Streptococcus mutans strain CBS 350.71 identifiable as OMZ 176. It is stated that the critical ingredient in dental plaque is water-insoluble polysaccharide with .alpha.-1,3-glucosidic bonds and that such polysaccharide material termed mutan is not attacked by dextranase.
Guggenheim et al., (1972), Caries Res. 6, p. 289-297) discloses that the extent of the dental plaque of rats is not significantly affected by the simultaneous use of a dextranase and a 1,3-glucanase (mutanase).
Hare et al. (1978), Carbohydrate Research 66, p. 245-264, found that a synergistic effect is obtained when hydrolysing and solubilizing oral glucans with a bacterial dextranase in combination with bacterial .alpha.-1,3 glucanase from Cladosporium resinae.
U.S. Pat. No. 4,438,093 (The Research Foundation for Microbial diseases of Osaka) describes oral compositions comprising a dextranase and a .alpha.-1,3-glucanase (mutanase), both being present in an amount of 0.5 to 100 enzyme units per gram of said oral composition, in an enzyme unit ratio of 1:2 to 2:1. Said dextranase is derived from a bacteria within the genus Corynbacterium and said .alpha.-1,3-glucanase is derived from a bacteria-within the genus Pseudomonas.
GB 2,206,585 (Dental Chem Co LTD) described a teeth cleaning agent containing hydroxyapatite as polishing agent, with a laevanase, dextranase and mutanase immobilized on the hydroxyapatite.
U.S. Pat. No. 5,145,665 (Henkel) discloses a composition for the care of the mount and teeth comprising a dextranase and/or a 1,3-glucanase for cleaving polysaccharides in the mouth.
FR 2,651,433 (DANA) concerns dentifrice products containing a dextranase to acts on recent plaque, a mutanase to acts on old and insoluble plaque, and a mixture or other enzymes having bactericide action.
U.S. Pat. No. 5,320,830 (Proctor & Gamble) describes toothpaste compositions for the reduction of plaque and gingivitis comprising a) a surfactant, b) an enzyme, c) chelating agent d) a fluoride source, e) a silica abrasive and d) a carrier. The enzyme is an endoglucanase, papain, a dextranase and/or a mutanase.